Such a control device, described for example in French Patent Application No. FR-2 424 157, is usually constituted by a control screw, received in a support fixed to the vehicle and comprising at one of its ends an element intended for pivoting, such as a ball for example. A socket integral with the optical assembly comprises a cavity adapted to house and fix in translation the pivoting element, whilst enabling it to rotate freely, in such a way as to form an assembly integral with the control screw.
The socket, which is often made of plastic, has a certain elasticity for enabling the pivoting element to be force fitted into it. Such a device is of simple design and satisfies the functional requirements, but has the disadvantage of being easily uncoupled.
In practice, such a mounting for the optical assembly, which is performed from the outside of the vehicle by presenting it in a direction parallel to the axis of the vehicle and in the front-to-rear direction, and engaging by force the pivoting elements by force in the sockets adapted to receive them, does not prevent accidental uncoupling or, in the case of a badly designed optical assembly, pulling it from the outside to disengage the pivoting elements from the sockets.